Speed-control means for high-frequency generators



Nov. 13, 1928. 1,691,222

0. BOHM SPEED CONTROL MEANS FOR HIGH FREQUENCY GENERATORS Filed April 2, 1926 INVENJ'OR OTTO BOHM BY jmfzfw ATTORNEY Patented Nov. 13, 1928.

UNITED STATES PATENT OFFICE.

OTTO FORM, 311mm, omnmr, ABSIGNOB TO GESELLSGHAIT EUR 1) TELEGBAPEIE K. B. H. EALLESCHES, OF BERLIN, GERMANY, A CORPORATION OI GERMANY.

airmen-00ml. mums ron mon-rmunncv onnnnaroas.

Application fled April 2, 198 Serial Rm endin Germany m 28, was.

My invention relates to speed regulating means and especially to speed regulators workin on the Tirrell principle. An 0 ject of my invention is to provlde a speed control means having a vibrating contact adapted to shunt a control resistance H for rapid successive periods of varying len h.

I other object of m invention is to pro- 10 vide a vibrating spee regulator in w ich the vibrations are under the control of a resonant circuit.

Another object of my invention is to pro vide a vibrating relay actuated in response to the movements of a primary vibrating relay, the vibratory currents from which are controlled by movements of a cam, actuated by speed responsive means.

In the art of the regulation of high frequency alternators it has been found essent-xal to maintain the speed at a constant value with very great accuracy. This has been found difiicult to do under the many varying requirements of high frequency alterna.

tor service.

My invention rovides a sim 1e means of applying the 1rrell princip e of the vibratory field control to the regulation of the speed of the motor driving a high fre- 80 quency generator.

By means of my invention I shunt a portion of the motor field resistance by means of a vibrated contactor rela ments of the relay are contro ed by current 85 from a vibrator-interruptor producing a convenient low frequency and means consisting of a pivoted cam cooperating with the vibratin member whereb the ratio between on periods and off perio s in the current output from the vibrating contact is controlled.

By this device I am enabled to obtain very sensitive and accurate speed regulation of the driving motor by means having a very much shorter natural period than the natural period of oscillation about an average value of the motor speed. By this means I obtain much closer speed regulation and freedom from hunting and speed rate oscillations.

Other objects and structural details of my The move producing invention will be apparent from the followmg descrlption when read in connection with the accompanying drawings, wherein:

The single figure is 'a diagrammatic representation of circuits and apparatus embodyingia preferred form of my invention:

eferring to the drawing I provide a motor D having a field winding 6 and drivmg; a high frequency generator G. A power supply 32 is provided for the motor D. ,A field resistance W is connected in series with Q the motor field winding 6 for control and regulatmg purposes. A portion of this resistance W is shunted by the contact R of the relay M. The coil of relay M is sup: plied by current from a source B in series with a contact K which cooperates with a movable cam The contact K is mounted upon a vibrator armature N which is driven by the usual magnet c, armature f and battery b. The contact K is preferably elastically mounted upon the vibrator armature N in order that it may have a. minimum efiect .upon the natural frequency of the vibrator and in order that changes in the position of impact with the cam S may produce as little 7 effect upon the frequency as possible. I

The cam S is mounted on a spindle A and preferably weighted so as to assume, by the influence of gravitation, a median position. The position of this cam is then controlled so by the deviation of the speed of the alternator from its proper value, The device for this deviation may conveniently assume t e form of resonant circuits and rectlfiers, connected to the output of the 85 radio frequency generator, and suppl an electro-magnetic rotatable device in such manner that an increase in speed will move the cam in one direction and a decrease in speed in the reverse direction.

This device ma conveniently assume the form of a coil Cl also mounted upon the spindle A and within the field of a magnet F. A pair of resonant circuits U and T may be coupled to the output circuit of the gen- 5 erator G, and tuned, one slightly above, and

' one slightly below, the desired frequency.

Rectifiers u and t are then provided and connected to the resonant circuits, as indicated, with the coil C in a portion of the common circuit.

In the operation, of the above described device of my invention the motor D drives the enerator G, the output from which may e su plied to a suitable transmitting circuit. T e value of the resistance W is then adjusted to such a magnitude that the motor D tends to run at a speed slightly below that required to produce the desired frequenc from the generator G. The vibrator may then be set into operation, whereupon the contact K will be caused to vibrate against the cam S making contact therewith for definite periods, at a definite frequency. Contact of the contactor K with the cam S closes the circuit through source B and coil M, causing an opening of the contacts R of the relay M, thereby inserting additional resistance in the field winding e of the motor D and causing its speed to tend to increase. The contacts R then close andopen at a frequency corresponding to the frequency of the vibrator N and remain open for a length of time determined by the time the contact K touches the cam S. The increase in speed of the motor D is then determined by the portion of the total time during which the contacts It are 0 en..

The disk S being pivoted, and of the shape shown in the drawing, a movement to t e left will bring a higher portion of the disk under the contact K and result in the contact K touchin the disk S for a longer portion of each vi ration period, while a movement of the cam S to the right will result in a lower portion of the cam coming under the contact K, and inthe circuit of source B being closed for a smaller portion of each vibration period. A full movement of the cam S to. the right may open the circuit at K completely and a full movement of the cam S to the left may close the circuit fully at K thus holding the contacts R steadily close or steadily open, and producing a maximum decrease or increase of the speed of the motor D.

The disk S may conveniently be moved by current in the coil C coacting with the field of the magnet F. This current is convenientl supplied from the output of generator G through the resonant circuits U and T. A decrease in s eed of the generator will result in the equency approaching more-nearly to the frequenc to which the circuit U is tuned and there y cause an increase in oscillatory current therein. The frequenc simultaneously recedes from the natural requency of the circuit T and such current as may have been flowing therein tends to decrease. The flow of vibratory current in curcuit U causes current to flow through the rectifier u and through the coil -Cinadirectionwhichmaybecausedto move the disk S towards the left, thereby causin contact K to touch for a longer period 0 time in each vibration, holding the contacts R of the relay M open for a longer proportionate integrated time, thus inserting a greater effective resistance into the field e of the motor D and causing an increase in motor speed.

Similarly an incrase in speed of the generator G will cause the frequency to approach the natural frequency of circuit, T and recede from that of circuit U thereby causing current to flow through rectifier t which sends a current through coil C in the reverse direction 'from' that furnished by rectifier u, moves the disk S to the right and by a similar uence of events causing a slowin down 0 the motor D.

By t means I am enabled to obtain a very accurate speed regulation of the motor D by apparatus based upon the Tirrell principle.

While I have shown but one embodiment of my invention in the fore oing drawings and descriptions it is capa le of various modifications therefrom without departing from the spirit thereof, and it is desired therefore that only such limitations shall be imposed thereon as are required b the prior art or indicated by the appended claims.

I claim as my invention:

1. A s regulating means comprisin a motor eld resistance, a shunting re ay connected thereto, means for actuating said shunting means comprising a current source and vibrato and adjustable contacts, means for ad usting said adjustable contact comprising a' rotatable cam, and speed responsive means actuating said cam, comprising means for producing a magnetic field, a coil mounted therein and connected to said cam, and means for electrically energizing said coil with a. current in one direction or the reverse according as the reg-v ulated speed departs above or below its regulated value.

2. In a speed regulating device, a field resistance, a relay for cutting said resistance into and out of circuit, a vibrator for actuating said relay, a cam for va ing the relative opening and closing perio s of the contact of said vibrator, whereby the period of insertion of the field resistance is varied, and means for adjusting the position of said cam in accordance with the speed of the controlled device.

3. In a speed regulating device, a field resistance, a relay for cutting said resist ance into and out of circuit, a vibrator for actuating said relay, a cam for varying the relative opening and closing periods of the contact of said vibrator, whereby the period of insertion of the field resistance is varied, and means comprising a coil associated with the controlled device and adapted to adjust the position of said cam in accordance with the speed of the controlled device.

4. A speed regulating device comprising a generator of alternating current and a motor for driving the generator, means for varying the speed of said motor, means .for actuating said speed varying means and means for controlling said actuating means comprising a pair of oscillatory circuits associated with the output of the generator and tuned respectively below and above the desired generator frequency, means for rectifying the currents of each of said oscillatory circuits, and a coil connected to said rectifying means adapted to vary said controlling means.

5. A speed regulating device comprising a generator of alternating current and a motor for driving the generator, a field resistance for said motor, a relay for cutting said resistance into and out of circuit, a vibrator for actuating said relay, a cam for varying the relative opening and closing periods of the contacts of said vibrator, whereby the period of insertion of the field resistance is varied, and means comprisin a pair of oscillatory circuits associated with the output of the generator and tuned respectively below and above the desired generator frequency for adjustin the position of said cam in accordance wit the speed of the controlled device.

6. A device of the kind described comprising a motor generator set, a variable field for said motor, means comprising an adjustable contact device for varying said field, and means in the output circuit pf said generator comprising two tuned circuits and rectifying devices connected thereto for controlling said adjustable contact whereby the frefluency of said generator may be contro ed.

7. In a device for maintaining the frequency of a motor driven generator, a contact comprising a vibrating portion and a rotating portion, means for periodically vibrating the first named portlon, a pair of resonant circuits detuned with respect to one another and coupled to the output circuit of said generator, rectifying means coupled to said resonant circuits, and means controlled thereby for rotating said rotating portion in accordance with changes in the regulated speed. I

8. In a speed regulating device, a contact comprising a vibrating portion, avrotating cam cooperating therewith, means for riodically vibrating said vibrating portion, and means comprising a magnetic field and coil mounted therein and connected to said cam for rotating said cam in accordance with changes in the regulated speed.

9. In a, device for maintaining constant the frequency of a motor driven generator, a contact device comprising a vibrating arm and a rotating cam, a magnetic field anda coil mounted therein and connected to said cam, means comprising a pair of resonant circuits coupled to the output circuit of said generator to be governed, rectifying means coupled to said resonant circuits for energizing said coil in accordance with changes in the frequenc of the governing generator wherebysai cam may be rotated.

DR. OTTO BOHM. 

